reg din_over='b0;
initial begin
  msg="test xx begin ,green";
  #1337 rstn = 1;
  din = 'h0;
  while(~din_over)begin
    #10ns {din_over,din} =  {din_over,din} + 'b1; 
  end
  //repeat(1000) @(posedge clk); din = 'b1000_0000_0000_0001;
  //repeat(1000) @(posedge clk); din = 'b1000_0000_0000_0000;
  //repeat(1000) @(posedge clk); din = 'b0000_0000_0000_0000;
  //repeat(1000) @(posedge clk); din = 'b0100_0000_0000_0000;
  //repeat(1000) @(posedge clk); din = 'b0100_0000_0000_0010;
  //repeat(1000) @(posedge clk); din = 'b0000_0000_0000_0010;
  //repeat(1000) @(posedge clk); din = 'b0000_1111_0000_0000;
  msg="PASS";
  //msg="FAIL";
end
